Earnings (Loss) Per Share Attributable to Quad/Graphics Common Shareholders (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net earnings (loss) from continuing operations	$ 10.2	$ (8.6)
Less: net earnings (loss) attributable to noncontrolling interests	0.0	0.0
Net earnings (loss) from continuing operations attributable to Quad common shareholders	10.2	(8.6)
Numerator
Net earnings (loss) attributable to Quad common shareholders	10.2	(12.4)
Loss from discontinued operations, net of tax	$ 0.0	$ (3.8)
Denominator
Basic weighted average number of common shares outstanding for all classes of common shares (in shares)	51.4	50.5
Plus: effect of dilutive equity incentive instruments (in shares)	1.4	0.0
Diluted weighted average number of common shares outstanding for all classes of common shares (in shares)	52.8	50.5
Earnings (loss) per share attributable to Quad common shareholders
Earnings (loss) per share attributable to Quad common shareholders, basic, continuing operations (USD per share)	$ 0.20	$ (0.17)
Earnings (loss) per share attributable to Quad common shareholders, basic, discontinued operations (USD per share)	0	(0.08)
Cash dividends paid per common share for all classes of common shares (USD per share)	$ 0	$ 0.15
Common Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0.9